[jQuery] help using parent()

[elubin]

I am trying to find the <div> parent of a <td> tag.  In the following
code, I do not understand why the alert shows 0 instead of 1??

<script type="text/javascript">
$(function(){
         var x = $('#row_3');
         var y = x.parent('div[id^=idSection_]');
         alert( y.length );
});
</script>


 <div id="idSection_A" style="display: block;">
        <table><tr><td id="row_1">eric 1</td></tr></table>
 </div>
 <div id="idSection_B" style="display: block;">
        <table><tr><td id="row_2">eric 2</td></tr></table>
 </div>
 <div id="idSection_C" style="display: block;">
        <table><tr><td id="row_3">eric 3</td></tr></table>
 </div>